Rope drive for swinging boom of a jib crane



Aug. 11, 1964 3,144,136

R. J. M AFEE ETAL ROPE DRIVE FOR SWINGING BOOM OF A JIB CRANE 2Sheets-Sheet 1 Filed May 6, 1963 INVENTORS. RICHARD J. M AFEE andCHARLES .STECKLE Attorney Aug. 11, 1964 v R. J. MCAFEE ETAL ROPE DRIVEFOR SWINGING BOOM OF A JIB CRANE 2 Sheets-Sheet 2 Filed May 6, 1963INVENTORS. RICHARD J. M AFEE and CHARLES STECKLE 9%,9 a

Attorney United States Patent Candless Township, Allegheny County, Pa.,assignors to United States Steel Corporation Filed May 6, 1963, Ser. No.278,025 2 Claims. (Cl. 212-66) The present invention relates generallyto cranes and, more particularly, to an improved rope drive for drivingthe boom of a jib crane.

Prior to our invention, swinging of a jib crane boom was frequentlyaccomplished by means of two ropes or cables, each of which was fastenedby one end to opposite sides of the free end of the boom. Each of theropes passed over a sheave and was attached at its other end to arotatable drum. Then, as the drum was rotated, the rope leading from theside of the boom in the direction in which it was desired to swing theboom would be Wound on the drum and the rope leading from the other sideof the boom would be wound off the drum.

A serious disadvantage inherent in the drive arrangement just describedwas the fact that although the rope pulling or towing the boom wasshortened" by being found on the drum as the boom moved from its centerposition and the other or trailing rope was lengthened by being woundoff the drum, the respective ropes were not shortened and lengthenedequally due to the arcuate path traveled by the free end of the boom towhich the ropes were fastened. The trailing rope lengthened faster thanthe towing rope was shortened so that a certain amount of slack wascreated in the trailing rope. This caused the boom to swinguncontrollably in the direction toward the towing rope and thus createda potential safety hazard for workmen in the vicinity of the jib craneboom.

It is, accordingly, one of the objects of our invention to provide animproved rope drive for swinging the boom of a jib crane whereby themovement of the boom is under control at all times as it is moved ineither direction from its center position.

It is a more specialized object of our invention to provide a rope driveof the character set forth in the above object which includes atraveling sheave arrangement for automatically taking up any slackcreated in the rope drive during swinging movement of the boom in eitherdirection from its center position.

These and other objects will become more apparent after referring to thefollowing specification and attached drawings, in which:

FIGURE 1 is an elevational view of a jib crane having the rope drive ofthe invention connected therewith;

FIGURE 2 is a diagrammatic illustration of the rope drive of theinvention; and

FIGURE 3 is an isometric view of a jib crane having the rope drive ofthe invention connected therewith.

Referring more particularly to the drawings, reference numeral 2designates an upright standard which may be in the form of an H-beamhaving a jib crane 4 mounted thereon. The jib crane 4 is provided with aboom 6 which extends from a post 8 journaled in a pair of verticallyspaced bearings 10 of the crane. A diagonal truss member 12 extendsbetween the boom and the post. The boom 6 swings in an arcuate pathradially of the crane in the usual manner. The boom is swung or drivento one side or the other by the rope drive of our invention which willnow be described.

The rope drive of the invention includes a rotatable drum 14 journaledfor rotation in a bracket 16 which is mounted on the standard 2 on theside thereof opposite "ice to and below the jib crane 4. A length ofrope or cable 18 is laid about the drum 14. An elevated way in the formof a trackway 2t) comprised of a pair of spaced parallel rails 22 eachmounted on supporting I-beams is located above the drum 14. The trackway20 extends in a horizontal plane transversely of an extension of thelongitudinal axis of the boom 6 when the boom is in its center positionas best shown by solid lines in FIGURE 2.

A carriage or trolley 24 comprising a pair of wheels 26 rotatablymounted on opposite ends of an axle shaft 23 is mounted for movementalong the trackway 26 with the wheels 26 traveling along the rails 22. Atiltable lever 30 is pivotally mounted intermediate its ends on the axleshaft 28 between the wheels 26. Sheaves 32 and 34 are mounted onopposite ends of the lever 30 for rotation in a vertical plane. Sheaves36 and 33 are mounted in fixed positions adjacent opposite ends of thetrackway 20 for rotation in a horizontal plane.

One end 40 of rope 18 extends from the drum 14, passes around verticalsheave 32 and horizontal sheave 36 to a point of attachment to the leftside of boom 6 adjacent its free end, as best seen in FIGURES 2 and 3.The opposite end 42 of rope 18 leads from the drum 14, passes aroundvertical sheave 34 and horizontal sheave 38 to a point of attachment tothe right side of the boom 6 adjacent its free end.

In operation, when it is desired to swing boom 6 to the right as seen inFIGURE 2, the drum 14 is rotated (manually or by suitable power means,not shown) in clockwise direction. Clockwise rotation of drum 14 causesthe end 42 of rope 18 to be wound on the drum so that the boom 6 ispulled or towed to the right, as shown by broken lines in FIGURE 2.While rope end 42 is being wound on the drum, it is tensioned and exertsa component of force against vertical sheave 34. At the same time, dopeend 40 is wound off the drum and slackened. The component force beingexerted on vertical sheave 34 by rope end 42 causes the right end oflever 30 to tilt downwardly and the carriage 24 to move to the rightalong trackway 20, as shown by broken lines in FIGURE 2. When the rightend of lever 36 tilts downwardly, vertical sheave 32 on the left end ofthe lever tilts upwardly and exerts tension on the slack rope end 40.This tension is increased by the carriage moving to the right along thetrackway until all of the slack is eliminated from rope 40.

When the drum 14 is rotated in counterclockwise direction, the boom 6will be swung to the left. At the same time, the carriage will move tothe left along the trackway, and the left end of lever 36 will be tilteddownwardly under tension of towing rope end 4%). When lever 30 tilts,vertical sheave 32 will be shifted upwardly. As the carriage moves tothe left with sheave 32 lifted upwardly, increasing tension will beexerted on the trailing rope end 42 to eliminate slack therefrom.

In installations where the boom of the jib is required to be swung arelatively short distance, the sheaves 32 and 34 may be mounted on thecarriage in non-tiltable relation thereto. Sufficient tension will beexerted on the trailing rope to eliminate slack therefrom solely bymovement of the carriage along the trackway.

Although we have shown and described carriage 24 as being mounted on topof a horizontally disposed trackway 20, it will be understood that thecarriage could be suspended from an overhead way, if desired. Further,if desired, the drum 14 could be mounted above the trackway 20 or itcould be positioned to rotate about a vertical axis in a horizontalplane common with the horizontal plane containing the trackway. In thelatter case, all of the sheaves 32, 34, 36 and 38 would preferably bepositioned to rotate about vertical axes.

While one embodiment of our invention has been shown Patented Aug. 11,1964 and described, it will be apparent that other adaptations andmodifications may be made without departing from the scope of thefollowing claims.

We claim: t

1. The combination with a jib crane having a boom pivoted at one end forswinging movement in a horizontal arcuate path radially of said crane ofa rope drive for swinging said boom which comprises a rotatable drumjournaled in a vertical plane adjacent the vertical plane containing thepivoted end of said boom, a length of rope laid about said drum, anelevated way adjacent the pivoted end of said boom, said way extendingin a horizontal plane transversely of an extension of the longitudinalaxis of said boom when said boom is positioned in the center of itspath, a carriage mounted for movement along said way, a first sheavejournaled on one end of said carriage and a second sheave journaled onthe other end thereof, a third sheave journaled at a fixed pointadjacent the end of said way toward said first sheave, and a fourthsheave journaled at a fixed point adjacent the opposite end of said way,one end of said length of rope extending from said drum and firstpassing around said first sheave and then around said third sheave to apoint of connection with the free end of said boom, and the other end ofsaid length of rope extending from said drum and first passing aroundsaid second sheave and then around said fourth sheave to a point ofconnection with the free end of said boom.

2. The combination with a jib crane having a boom pivoted at one end forswinging movement in a horizontal arcuate path radially of said crane ofa rope drive for swinging said boom which comprises a rotatable drumjournaled in a vertical plane adjacent the vertical plane containing thepivoted end of said boom, a length of rope laid about said drum, anelevated way adjacent the pivoted end of said boom, said way extendingin a horizontal plane transversely of an extension of the longitudinalaxis of said boom when said boom is positioned in the center of itspath,a carriage mounted for movement along said Way, a 'tiltable levercarried by said carriage, said lever being tiltable about a horizontalaxis extending transversely of said way, a first sheave journaled on oneend of said lever and a second sheave journaled on the other endthereof, a third sheave journaled at a fixed point adjacent the end ofsaid way toward said first sheave, and a fourth sheave journaled at afixed point adjacent the opposite end of said way, one end of saidlength of rope extending from said drum-and first passing around saidfirst sheave and then around said third sheave to a point of connectionwith the free end of said boom, and the other end of said length of ropeextending from said drum and first passing around said second sheave andthen around said fourth sheave to a point of connection with the freeend of said boom.

References Cited in the file of this patent UNITED STATES PATENTS3,057,484 Trevisan Oct. 9, 1962 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No., 3,, 14M 136 August 11, 1964 Richard J, McAfeeet ale It is hereby certified that error appears in the above numberedetent requiring correction and that the said Letters Patent should readas corrected below.

Column 1 line 26, for "found" read wound column 2 line 31 for "be "woundon" read be "wound on" line 36 for "dope" read rope Signed and sealedthis 24th day of November 1964c (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer a Commissioner ofPatents

2. THE COMBINATION WITH A JIB CRANE HAVING A BOOM PIVOTED AT ONE END FOR SWINGING MOVEMENT IN A HORIZONTAL ARCUATE PATH RADIALLY OF SAID CRANE OF A ROPE DRIVE FOR SWINGING SAID BOOM WHICH COMPRISES A ROTATABLE DRUM JOURNALED IN A VERTICAL PLANE ADJACENT THE VERTICAL PLANE CONTAINING THE PIVOTED END OF SAID BOOM, A LENGTH OF ROPE LAID ABOUT SAID DRUM, AN ELEVATED WAY ADJACENT THE PIVOTED END OF SAID BOOM, SAID WAY EXTENDING IN A HORIZONTAL PLANE TRANSVERSELY OF AN EXTENSION OF THE LONGITUDINAL AXIS OF SAID BOOM WHEN SAID BOOM IS POSITIONED IN THE CENTER OF ITS PATH, A CARRIAGE MOUNTED FOR MOVEMENT ALONG SAID WAY, A TILTABLE LEVER CARRIED BY SAID CARRIAGE, SAID LEVER BEING TILTABLE ABOUT A HORIZONTAL AXIS EXTENDING TRANSVERSELY OF SAID WAY, A FIRST SHEAVE JOURNALED ON ONE END OF SAID LEVER AND A SECOND SHEAVE JOURNALED ON THE OTHER END THEREOF, A THIRD SHEAVE JOURNALED AT A FIXED POINT ADJACENT THE END OF SAID WAY TOWARD SAID FIRST SHEAVE, AND A FOURTH SHEAVE JOURNALED AT A FIXED POINT ADJACENT THE OPPOSITE END OF SAID WAY, ONE END OF SAID LENGTH OF ROPE EXTENDING FROM SAID DRUM AND FIRST PASSING AROUND SAID FIRST SHEAVE AND THEN AROUND SAID THIRD SHEAVE TO A POINT OF CONNECTION WITH THE FREE END OF SAID BOOM, AND THE OTHER END OF SAID LENGTH OF ROPE EXTENDING FROM SAID DRUM AND FIRST PASSING AROUND SAID SECOND SHEAVE AND THEN AROUND SAID FOURTH SHEAVE TO A POINT OF CONNECTION WITH THE FREE END OF SAID BOOM. 